The present invention relates in general to rotary power lawn mowers, and more specifically to a safety rotary cutter for rotary type lawn mowers.
Conventional rotary lawn mowers are provided generally with a single steel blade sharpened at two opposite leading edges for cutting grass during rotation of the blade. The blade is also generally formed with a trailing edge twist to create air motion at a sufficient velocity to expell cut grass through a discharge chute in the shroud surrounding the blade.
Rotary mowers provided with steel blades have caused many injuries to users' fingers and feet through direct contact with the rotating blade, and other injuries and property damages by projection of stones, pebbles, or other objects hit by the rotating blade. Attempts have been made in the past to provide guards for the steel blade of a rotary mower, or to replace the steel blades with plastic cutters, whips and wires, but most of those attempts have met with limited success as a result of being either too complicated, too costly, or interfering to interfere with efficient grass cutting.
According to a report by the Consumers Products Safety Commission published in the Federal register, Feb. 15, 1979, Part V, there are approximately 77,000 persons injured each year by contacting the moving blades of walk-behind lawn mowers. As a result of the Commission's findings, new safety standards for lawn mowers have been adopted, effective Dec. 31, 1981. The most significant requirement under the new standards is that of a clutch-brake system capable of stopping the blade of a rotary power mower within three seconds. Such a requirement, even if it can be met, will considerably increase the price of lawn mowers.